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The bite that kills
By Renu Warnasuriya and Priyanwada Ranawaka
One lick, scratch or bite could decide your fate. To many it comes as a shock… a nasty one at that. Nearly 400,000 Sri Lankans are bitten by dogs each year and only 200,000 of them seek treatment; the rest of them, put their life in danger of a fatal disease, when it can be prevented.

Rabies caused by the Rhabdo virus is a disease that can affect dogs, cats, mongoose, cows, goats, horses, monkeys, polecats, jackals and other warm-blooded animals, particularly mammals. If any animal or human develops the symptoms of this disease, it is invariably fatal. However, rabies can be prevented, if the necessary precautions are taken. Ninety-seven percent of the Rabies cases in Sri Lanka are caused by dogs, 2% by cats and 1% by the mongoose.

The government spends around Rs. 200 million annually on rabies' treatment, which includes the Anti- Serum and the full course of the Anti-Rabies vaccine. Horse serum and the Intradermal technique are used to keep costs at an affordable level. In the Intradermal technique, which was introduced in 1998, only 2ml of the vaccine is used as opposed to the 5ml used in the Intramuscular technique. Both techniques however have the same effect.

"Rs. 2000 to 3000 is spent on one person for the full Anti-Rabies treatment. In special cases where the Human Serum is used, the cost is more," said Director, Public Health Veterinary Services Dr. P. A. L Harischandra. To get the full treatment at a private hospital, a patient would have to spend nearly Rs. 45, 000. This is mainly because private hospitals generally use the Human Serum (which is more expensive than the Horse Serum) and the Intramuscular technique.

How do you know that you have been bitten by a rabid dog? Red eyes, saliva drooling, biting everyone and everything… that's the common picture of a rabid animal. But it's not always so evident.

Dr. Omala Wimalaratne, Medical Virologist and Vaccinologist of the Department of Rabies and Vaccines, Medical Research Institute, explained that there are two types of rabid animals. The 'furious type', shown by 80% of humans and animals have these symptoms while the other 20% belong to the 'paralysis type'. The latter is more inactive and shows difficulty in movement due to the paralysis of the muscles. "The animals sometimes act as if a bone is stuck in the throat," says Dr. Wimalaratne adding that many pet owners attempt to relieve the animal by putting their hands in the mouth to remove the bone. Unfortunately this often results in a bite.

Humans are accidental hosts to this fatal disease. A healthy person can be infected if he is scratched, bitten or licked on the mucous membranes (eyes, lips) or an unhealed, uncovered wound, by a rabid animal. Though the virus cannot penetrate if the skin is intact, even a small break in the skin is enough for it to enter the body. The virus is highly concentrated in the animal's saliva, while the tears and milk can also carry the virus.

Once infected, there is an incubation period (the time taken for the person to develop the disease), which in the case of Rabies may be as short as a week or as long as a year. Generally however it is between 30 - 90 days. At times even after the wound is healed the victim may feel numbness or a “pins and needles" sensation around the bite area. Weakening of the limbs could also be an early symptom of Rabies. However any animal or human that shows symptoms of Rabies will die within 14 days of the symptoms appearing.

All the symptoms and signs are related to the nervous system, which is affected by the virus. It spreads all over the body and could lead to cardiac arrest and other such effects. Most people invariably die of respiratory failure. Very often the breathing and swallowing muscles, including the vocal cords get paralysed. This has led to the common belief that Rabies patients sound and behave like dogs. The reality is that the paralysed vocal cords affect the person's ability to speak, making their words sound like barks.

Among the many programmes being carried out by the Department of Public Health Services to curb the spread of rabies is the mass vaccination of domestic dogs, where nearly 800,000 domestic dogs are vaccinated each year.

In 2001, the vaccination programme was extended to stray dogs, with the invention of the Auto Vaccine Device. Invented in Sri Lanka this device enables vaccination of any freely moving dog. Roughly 75,000 strays are vaccinated each year with this device. A shortage of vehicles has, however, restricted this programme to a few areas including Kurunegala, Colombo, Gampaha, Kandy and Kegalle. The oral vaccination programme, which was introduced, recently is so far being carried out in the Puttalam District. This system is not yet practised on a large scale due to its heavy cost. With the co-operation of local authorities in the Puttalam District, the programme has been quite successful.

The number of rabies deaths was brought down from 300 (in the '70s) to 62 last year. But there has been a slight rise in the number of cases reported last year. " Till the end of this year we don't know what the situation will be," says MRI's Dr. Wimalaratne. "We need to realize the gravity of the situation and strengthen our control programmes. Many people don't get treatment due to ignorance." "It's a sad situation," she says, "because once you get the symptoms it is too late."

Precautions and treatment
If bitten by an animal the wound should be immediately washed with soap and water for at least 10 minutes, after which it should be cleaned with antiseptic. The next important step is to go to the nearest government hospital for medical advice.

It is important that a trained doctor examines the wound and determines the appropriate treatment, which depends on many factors including the site (how close it is to the brain), extent (number of bites, depth of the bite) of the wound and whether the animal is a stray or domestic one and its immunization history. If bitten by a vaccinated animal it is important to take the animal's vaccination book when visiting the doctor.

If it is a more serious bite, patients are given Anti-Serum, which consists of a series of injections, around the wound to kill the virus in the wound, providing temporary protection. The Anti-Serum must be followed by a course of Anti-Rabies vaccines, which will be either four or five doses. For a minor bite, however the Anti- Serum may be unnecessary and the normal course of vaccines is sufficient. Since unnecessary vaccinations could lead to long term effects it is important to get treatment only under medical advice, which should be followed strictly.

The Anti-Rabies vaccination does not provide lifetime immunization. If a person is bitten again after a full course of vaccine it is important to seek medical advice, as the necessary treatment is very different to the treatment given for a first bite.

In the case of a rabies’ death, it is important to inform the Public Health Inspector who will instruct the family about the necessary procedure that includes the coffin being sealed and the body preferably being cremated as early as possible.

As surprising as it may seem even adorable puppies may be carrying the virus. A puppy's first vaccine should be given at six weeks and then a booster in three months. Thereafter the dog should be vaccinated annually.

If the bite is from a domestic pet, the animal should be kept caged for 14 days after the bite. Meanwhile the victim should seek a doctor's advice and begin the course of vaccinations. After 14 days of observation if the animal is healthy and shows no signs of the disease, the rest of the course is stopped. It is essential to immunize the animal after the observation period is over.

If a rabid animal bites a dog even after it has been immunized, the dog would need a booster dose and should be carefully observed for three to four months. However if the dog that is bitten has not been immunized the WHO recommendation is that it should be destroyed.

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